Non-linear genetic diversity and notable population differentiation caused by low gene flow of bermudagrass [Cynodon dactylon(L.) Pers.] along longitude gradients

Abstract

Background Environmental variation related to ecological habitat is the main driver of plant adaptive divergence. Longitude plays an important role in the formation of plant population structure, indicating that environmental differentiation can significantly shape population structure. Methods Genetic diversity and population genetic structure were estimated using 105 expressed sequence tag-derived simple sequence repeat (EST-SSR) loci. A total of 249 C. dactylon (L.) Pers. (common bermudagrass) individuals were sampled from 13 geographic sites along the longitude (105°57′34″–119°27′06″E). Results There was no obvious linear trend of intra-population genetic diversity along longitude and the intra-population genetic diversity was not related to climate in this study. Low gene flow (Nm = 0.7701) meant a rich genetic differentiation among populations of C. dactylon along longitude gradients. Significantly positive Mantel correlation (r = 0.438, P = 0.001) was found between genetic distance and geographical interval while no significant partial Mantel correlation after controlling the effect of mean annual precipitation, which indicated geographic distance correlated with mean annual precipitation affect genetic distance. The genetic diversity of C. dactylon with higher ploidy level was higher than that with lower ploidy level and groups of individuals with higher ploidy level were separated further away by genetic distance from the lower ploidy levels. Understanding the different genetic bases of local adaptation comparatively between latitude and longitude is one of the core findings in the adaptive evolution of plants.

Directional Breeding Generates Distinct Genetic Diversity in Hybrid Turf Bermudagrass as Probed with Simple Sequence Repeat Markers

“…A study of the population structure of 296 bermudagrass genotypes from different latitudes using 153 EST-SSR markers reported more genetic diversity in higher ploidy levels and lower latitudes in China (Zhang et al 2019), and that the population structure follows latitudes with notable admixtures and no isolation by distance. A recent genetic diversity and population structure study of common bermudagrass collection using EST-SSR markers reported notable population differentiation along longitude gradients caused by low gene flow (Zhang et al 2021). The population structure along the latitude gradient implies the existence of genetic variation for cold adaptation among bermudagrass germplasm, whereas the longitudinal gradient implies population isolation.…”

Directional Breeding Generates Distinct Genetic Diversity in Hybrid Turf Bermudagrass as Probed with SSR Markers

“…They also reported population structure to follow latitudes with notable admixture and no isolation by distance. A recent genetic diversity and population structure study of common bermudagrass collection using EST-SSR markers reported notable population differentiation along longitude gradients caused by low gene flow [45]. The population structure along the latitude gradient implies the existence of genetic variation for cold adaptation among bermudagrass germplasm while the longitudinal gradient implies population isolation.…”

Research Article Population structure and genetic relatedness in Brazilian Bermudagrass from sugarcane plantations

“…They also reported that environments with higher temperatures and high precipitation rates could favor higher rates of variability within populations; but if there is a low gene flow rate, this variability could be exhausted over time. Zhang et al (2021), using 105 EST-SSRs, reported low gene flow, with rich genetic differentiation, among populations of C. dactylon along longitude gradients. The authors stated there was no clear linear trend of intra-population genetic diversity along longitude, and the intra-population genetic diversity was not related to climate.…”